1. Field of the Invention
This disclosure is related to a controller for a power system within a structure such as a residence or business. Specifically, the control system generally serves to provide centralized control of power distribution on both AC and DC circuits wired into the structure.
2. Description of the Related Art
Today there is an increasing emphasis on energy efficiency, not only for the individual and the company, who are the energy consumers, but also for energy providers. This is especially true for electrical energy. The Energy Information Administration (EIA) estimates that in 2011 about 461 Billion kW hours of electricity were used in the USA by the residential and commercial sectors. Electricity used for lighting was equal to 17% of total electricity consumed by both of those sectors. Residential lighting consumption was about 186 Billion kilowatt hours (kWh) of electricity in the USA, or about 13% of all residential electrical consumption. For the commercial sector, lighting consumed about 275 Billion kWh of electricity or 21% of all the commercial sector electricity.
This large consumption of electricity for lighting has led to governmental regulation to utilize more efficient lighting devices and the manufacture of the incandescent bulb (e.g. the lightbulb as originally contemplated in U.S. Pat. No. 223,898 to Edison) has essentially been halted. Instead, lighting is being increasingly supplied through compact fluorescent light (CFL) bulbs and halogen bulbs and to an increasing percentage, light emitting diode (LED) bulbs.
As trends in building new houses increases square footage, the energy consumption of future buildings generally, and specifically the percentage consumed by lighting, will likely continue to rise without a major transition to the use of more efficient light sources. LEDs, for the same level of lumen light emission as an incandescent bulb, can consume as little as one sixth to one tenth of the power of an incandescent bulb. Use of LED technology for lighting, therefore, offers the residential home owner the opportunity to reduce their electrical energy consumption by 10% if used consistently. This opportunity has resulted in a plethora of new light bulbs and new fixtures which utilize LEDs hitting the market.
Generally, the LED bulbs and fixtures that are provided currently are configured to interface into existing fixtures normally utilizing an Edison screw connector in the United States and a universal bayonet type format in many European countries. The LED fixtures are therefore designed to replace traditional incandescent bulbs in existing sockets and fixtures already installed into an older structure. They are, effectively, LED light bulbs where the LEDs and associated control electronics are all self-contained and provided in a format which can simply be attached in place of a traditional incandescent bulb onto the internal AC wiring of the structure.
The “light bulb” carrying the LEDs will, therefore, generally be configured to interface with the existing residential or commercial AC supply (normally 110 V 60 Hz in the US) and will need to supply everything to allow the LED device to operate with simple wired connection to an AC power source. LEDs are, however, direct current (DC) driven solid state devices and, moreover, are low voltage DC devices. The result is that today each “LED bulb” has to carry its own AC to DC conversion electronics to allow for the LED to obtain useable power from the AC based wiring infrastructure in the building. Further, they generally have to include electronics to bleed off excess wattage to make sure that there is not too much power provided to the LEDs.
This drives up cost as the electronics must be mounted on each bulb, and are discarded when the bulb is replaced. It also decreases overall reliability of the LED bulb because it provides for a larger number of electronic components that can fail (LEDs are inherently 40 times more reliable than incandescent filaments, but LED bulbs generally do not show the same multiplier of reliability). Further, individual control electronics also reduce the overall efficiency of the LED lighting system as the AC power has to be converted into DC power at a variety of points resulting in creation of waste heat.
Still further, the heat generated from this conversion can be problematic. Certain LED bulbs can only be installed in certain orientations without presenting possible fire hazards, and, even if heat can be controlled, the creation of waste heat within the LED bulb structure can result in further reliability issues due to potential damage. Thus, while the use of retrofit LED lighting has dramatically reduced power consumption in structures which use them consistently, it is clear that they still operate very inefficiently, and cost much more, than their inherent capability.
If there was a way to provide for DC current to be provided directly to lighting systems, the cost of the bulbs could be dramatically lowered and many of the above problems would be avoided as control electronics could be removed from the LED bulb meaning that the LED bulb itself would need only include the basic LEDs and DC power handling components. Further, a DC power rail within a structure is much safer than an AC rail. It is generally difficult to cause severe damage to the human body with DC power because it has little effect on human electromechanics. However, essentially every structure built or modified since the electrical era began around 100 years ago has been built with internal AC power rails and the power grids of the vast majority of locales are AC power grids.
Certain structures are beginning to take advantage of the benefits of LED lighting directly by providing installed LED lighting which utilizes batteries instead of being connected to the AC grid, or which can be directed to direct energy generation sources such as solar panels which readily produce DC power. While this can be an effective solution, it is far from efficient as even while LEDs can run for many years off of batteries, this arrangement produces a large amount of battery waste and many direct generation sources are only useable in certain circumstances.
The creation of a DC power rail within a residential or commercial building can dramatically change the equation. In the first instance, the need for individual AC to DC conversion for every light or light fixture goes away. Cost is reduced and reliability increased. Furthermore in the event of an outage of the main AC supply, a simple backup of a battery or fuel cell will suffice to ensure that lighting and other potentially essential infrastructure connected to the DC rail is maintained. Further, add on electricity generation systems (such as solar panels) can be used to generate DC power which can be fed directly into the rail. However, such a solution has generally not been possible with current lighting systems or structures.
The cost of wiring (independent of the actual fixture costs) in a new structure generally has two components, first the cost of the wire itself, and second, the cost of the labor to install it. In residential houses the major driver is the labor, but the material is not inconsequential at 20 to 30% of the total cost. The wiring of residential and even commercial lighting is generally straightforward for devices such as outlets and lights where one light or bank of lights is controlled from one switch. However, there are times, such as at a stairwell, hallway, or certain rooms with multiple entrances and exits, where a light is controlled from two or more locations. Similarly fans and plug outlets are sometimes controlled from two or more locations.
In these types of arrangements, the two-way, three-way and higher way arrangement of switches (where the same fixture can be controlled from multiple switches) requires significantly more labor time from more experienced electricians, specialized components, and more wire to interconnect the operation. In effect, if a system is wired simply where the wires connect directly to the outlet from both switches, one has to turn both switches off to turn the outlet off, while any one of them being on will result in power. This does not allow for free toggling. For example, wiring a single bulb to be controlled from two switches with free toggling (where any change on either switch toggles the lights status) requires replacing the standard two-way switches normally used in lighting applications with three-way switches (or an equivalent circuit), wired in a particular pattern. For three or more switches, three-way and four-way switches are required in particular patterns. This complication therefore costs significantly extra to install both in parts (due to the more complicated switches and additional wiring) and labor (to make sure they are connected correctly).
The cause of this complication is that the operation of the switch is physically connected to the functionality of the switch. That is, a light switch, quite literally, is connected into the wire and directly acts as a mechanical switch to allow or stop electrical flow. Because each wire leading into an outlet is either on or off, it can be impossible to provide for the ability to freely toggle power from any of the switches without adding additional paths which reconnect the flow in different ways.
One major problem in all electrical wiring systems is that once an electrician has wired the system during construction (which usually occurs when only the skeleton of the structure exists and it is easy to construct things that will eventually be within walls), the only way to change the system is a physical rewiring of the system. This usually requires the re-running of wires, as well as changes to the switches themselves. This is usually very costly as it can require tearing the surfaces (usually drywall) off of walls to access the wires, or it requires sophisticated tools to thread new wires through difficult to access (and even to see) passageways.